Non-destructive testing of post-tensioned concrete elements using Ground Penetrating Radar (GPR) and Ultrasound Tomography (UT)

Recently, there has been a growing focus on the vulnerability of infrastructure, particularly bridges, due to emerging issues that may threaten the safety of commuters. A significant number of major bridges that are over 50 to 60 years old suffer from insufficient maintenance, aging materials, and rapid structural integrity deterioration. In response, governments have initiated comprehensive bridge inspection campaigns, based on national Guidelines, to assess their current condition. This initiative provides the basis for the development of rehabilitation programs to restore viable infrastructure and identify alternative solutions for those beyond repair. This thesis focuses on evaluating the applicability and reliability of non-destructive techniques employed in bridge inspections, specifically. Ground Penetrating Radar (GPR) and Ultrasound Tomography (UT). The study aims to clarify the strengths and limitations of these methods by offering a comprehensive theoretical foundation, explaining the underlying principles, and examining their applicability and beneficial outcomes. Therefore, two distinct experimental campaigns were conducted under controlled laboratory conditions, providing valuable case studies that closely mimic real-world bridges, in particular post-tensioned beams. Tendon ducts were filled with grout and tendons, along with scenarios simulating defective grouting. The specimens include variable spacing between stirrups and varying tendon duct depths. These controlled experiments offer a practical framework for analyzing the factors influencing the effectiveness of the two methodologies. The laboratory findings contributed to more reliable assessments of structural integrity and grouting conditions, ultimately supporting effective maintenance and rehabilitation strategies for bridges. This work highlighted the importance of integrating advanced technology into infrastructure management to ensure the safety and longevity of vital transportation networks.